1. Field of the Invention
This invention relates to electron-beam (E-beam) lasers and especially to the suppression of high-frequency acoustic waves generated in E-beam lasers.
2. Description of the Prior Art
The non-uniform energy distribution pattern resulting from the shadow effect of the foil support ribs in E-beam-pumped, gas-laser cavities generates high-frequency acoustic waves transverse to the gas flow. Experimental data indicates that these acoustic waves persist within the cavity and affect the density and refractive index of the gaseous medium, thereby changing the optical path lengths of different portions of the laser beam. The uneveness of the optical path lengths reduces the quality of the laser by introducing an optical phase distortion in the coherent output beam. The influence of the acoustic waves is unacceptable for good optical homogeneity of the medium and the interpulse time interval has to be extended to allow the acoustic waves to attenuate sufficiently. This lowers the pulse repetition rate and effective output efficiency of the laser.